A signal lamp of the afore-mentioned type is disclosed by DE 33 26 199 A1. This prior art signal lamp as used with automotive vehicles is provided with a pink-colored closure plate and, in the interior thereof, includes another colored filter, it being possible to generate, by selecting a predetermined color for the said filter, a red, yellow or even white signal light. In order to cause the closure plate, in the turned-off condition of the light source of the signal lamp, to appear despite its pink color in bright red not or only negligibly affected by the color of the internal filter, red-colored strips are provided in the lamp between the inner filter and the closure plate. However, all of the prior known strip arrangements involve certain disadvantages. Either only a small quantity of the amount of light emitted by the light source or only part of the surface of the closure plate can be used for the generation of the signal. Moreover, some arrangements are only marginally suitable to minimize in the turned-off condition, the influence of the inner filter on the color of the closure plate. Finally, even large-scale technical efforts cannot entirely prevent an influence of the red-colored strips on the color of the signal light from occurring.
EP 0 211 742 A1 discloses a signal lamp foregoing the use of color-impermeable webs. In this prior art signal lamp the closure plate is provided, in strips, with a color filter imparting a certain color to the light rays passing through this area. Coupled ahead of the areas of the closure plate clear of filters, in a protruding plane, is a filter, thereby imparting a certain color also to the light rays passing through that area. At a certain distance from the closure plate, the whole light passing through the closure plate is of a homogenous color. In that signal lamp it is considered to be disadvantageous that the closure plate comprises alternately colored and transparent strips so that the outward appearance is not very attractive. Moreover, due to the plurality of series-arranged color filters the light yield is reduced, especially as regards the generation of white light; in this respect the red color of the colored closure plate has to be filtered out by a subtractive color mixture. Another disadvantage resides in that the closure plate can be designed only in a very light red or pink as a more intensive red would result in relatively high light losses.
It is, therefore, an object of the invention to provide a signal lamp which, in turned-off condition, conveys the impression of an intensive red, involving low light losses.
This problem, in the practice of the invention, is solved in that the closure plate has a continuous coloring, the closure plate is subdivided into segments of varying thicknesses and that the light filter is provided with a recess.
Due to the continuous coloring of the closure plate, the latter appears in a uniform, for example, red color which can be an intensive red. The subdivision of the closure plate into segments of varying thickness and the recesses provided in the light filter involve the advantage that the light emitted by the light source, in the areas in which the segments are of a high plate thickness, passes through the recesses of the light filter and is, therefore, not additionally attenuated by the light filter.
Provided in the areas of the segments of low plate thickness are the sections of the light filter located between the recesses where the light is colored. Although the color of the light weakens the intensity thereof, the light will only have to pass through the segments of the closure plate having a low plate thickness. In view of this design, the signal lamp, in the turned-off condition, has an intensive red coloring and, in the turned-on condition, a high light intensity as only the part of the light required to pass through the segments of a low plate thickness, must pass through an additional light filter.
According to another embodiment, the segments of varying plate thickness have different widths. It is especially the segments of a lower plate thickness that are narrower designed than the segments of a higher plate thickness, thereby imparting to the signal lamp a substantially uniform appearance as the segments of a lower plate thickness appearing slightly lighter are of a very low width so that the general impression is almost unaffected.
Preferably, at least one lens system is provided between the light filter and the closure plate. This lens system has the function to dissipate at least a part of the light passing through the closure plate causing the light to additively mix after passage through the closure plate.
According to another embodiment, the lens system is formed of lenses located on the segments of a high plate thickness, with the lenses and the segments being preferably integrally formed. This design involves the advantage that a separate component comprising the lens system can be eliminated as the lens system is provided directly on the rear and on the inner face, respectively, of the closure plate.
According to another embodiment, a lens system is provided between the light source and the light filter. Due to the lens system, a part of the light emitted by the light source is focused and emitted especially through the light filter and through the segments of the low thickness closure plate arranged therebehind. Due to the focusing of the light this focused light is pointedly led through the segment of the closure plate concerned.
The lens system, advantageously, is formed of the lenses provided on the light filter, with the lenses and the lens filter being preferably formed integrally, thereby eliminating the use of a separate component comprising the lens system. The lenses of the two lens systems can be of any desired design, i.e. they can either be of a concave and/or convex configuration. Moreover, the rear side and/or the front side of the light filter and/or of the closure plate can be in the form of a lens system.
According to another embodiment, the lens system comprises recesses in the area of the light filter recesses. According to this form of embodiment, lenses are provided only where a light filter for the light emitted by the light source is provided so that only the light passing through the light filter is deflected, with the lenses of the two lens systems being either in the form of cylindrical tangs, rotation-symmetrical lenses or of any other suitable configuration.
Preferably, the light of the light source is refracted either by the lens system associated to the light filter or by the light system associated to the closure plate which involves the advantage that a part of the light is not deflected by both lens systems but each lens system rather deflects a special area or share of the light emitted by the light source depending on the configuration of the respective lens system.
According to a preferred embodiment, the focal length of the lens system associated to the light filter is within the area of the segments of lower plate thickness, preferably, on the inner or outer face of the closure plate, thereby attaining the advantage that the light deflected by this lens system exclusively passes through the segments of lower plate so that the light intensity is only negligibly reduced.
According to another embodiment, it is provided that the focal length of the lens system associated to the closure plate is at a greater distance from the outer surface once the thickness difference within the segments of higher plate thickness is reduced, thereby making uniform the color intensity of the whole of the closure plate.
Preferably, the distance of the light filter from the inner face of the closure plate varies at varying signal colors, thereby enabling the share of the light passing through the segments of higher plate thickness and the segments of lower plate thickness, respectively, to be precisely controlled.
Advantageously, the desired signal color can be generated by color subtraction and a subsequent color addition. Due to the color subtraction, those parts of the color are generated which as a result of the color addition, subsequently, lead to the desired signal color. Due to the color addition the color intensity is enhanced.
FIG. 1 shows a first form of embodiment of the signal lamp according to the invention, intended, for example, for a white signal light.
FIG. 2 shows another form of embodiment of the signal lamp according to the invention, intended, for example, for a red signal light.